SIMBAD references

M. Hamuy and M. Roth, Carnegie Observatories, report that a spectrogram (range 380-930 nm) of SN 2003id (cf. IAUC 8201, 8203), obtained on Oct. 16.27 UT with the Dupont 2.5-m telescope (+ WFCCD) at Las Campanas, reveals unusual features. While the spectrum is characterized by strong absorptions between 466 and 536 nm (presumably due to Fe II blends) that are seen in other type-Ic events, a strong unidentified absorption centered at 562 nm distinguishes it from other type-Ic or type-Ib supernovae. This feature is blended with another strong absorption centered at 579 nm. The spectrum shows a strong Ca II triplet line exhibiting a broad P-Cyg profile; adopting the NED host-galaxy recession velocity of 2288 km/s, the minimum of the Ca II triplet at 826 nm implies an expansion velocity of -13000 km/s, which is very high for a supernova that is at least one month old. The optical lightcurves are also unusual: the V-band flux decreased by about 0.25 mag between Sept. 19 and 25; a plateau phase (V = 17.25) ensued through Oct. 3; and the flux has been dropping afterwards, reaching V = 18.6 on Oct. 16. Further observations at optical and other wavelengths would be useful.